SpamTitan Sender List Management

Overview

SpamTitan maintains two key sender policy lists that override the spam filtering engine: the allowlist (trusted senders whose mail is always delivered) and the blocklist (blocked senders whose mail is always rejected or quarantined). Proper list management is essential for MSPs to balance effective spam filtering against business continuity — preventing false positives from disrupting client workflows while blocking persistent unwanted senders.

Key Concepts

Allowlist (Trusted Senders)

The allowlist contains senders whose email is delivered directly to users' inboxes, bypassing spam scoring. Use the allowlist for:

• Legitimate business partners whose emails are frequently misclassified as spam
• Bulk notification systems (monitoring alerts, business SaaS tools) that trigger spam rules
• Internal relay servers or third-party mailing services used by the client
• Vendors with IP-based reputation issues beyond their control

Caution: Allowlisting bypasses spam filtering entirely. Only allowlist senders you have explicitly verified as legitimate. Attackers frequently spoof trusted sender addresses.

Blocklist (Blocked Senders)

The blocklist causes matching emails to be immediately rejected or quarantined, regardless of their spam score. Use the blocklist for:

• Known spam campaigns with persistent sending addresses
• Domains that have been identified as malicious or compromised
• Senders that bypass spam scoring with low-score messages but are clearly unwanted
• Former vendors or partners whose mail is no longer wanted

Entry Types

Both lists support multiple entry scopes:

• Email address — e.g., [email protected] — matches only that exact address
• Domain — e.g., @example.com or example.com — matches all senders from that domain
• IP address — e.g., 203.0.113.45 — matches email from a specific sending IP

Per-Domain vs. Global Lists

In multi-tenant SpamTitan deployments, lists can be applied at two scopes:

• Global — Applies to all client domains managed by the gateway
• Per-domain — Applies only to a specific client domain

Always prefer per-domain entries in MSP environments to avoid unintended cross-client effects.

API Patterns

List Allowlist Entries

spamtitan_list_allowlist

Parameters:

• domain — Filter entries for a specific client domain (omit for global entries)
• type — Filter by entry type (email, domain, ip)
• page — Page number (1-based)
• limit — Results per page (max 200)

Example response:

{
  "entries": [
    {
      "id": "al-00491",
      "entry": "[email protected]",
      "type": "email",
      "domain": "clientcorp.com",
      "added_at": "2026-01-15T10:30:00Z",
      "added_by": "[email protected]",
      "notes": "PagerDuty monitoring alerts — falsely quarantined"
    },
    {
      "id": "al-00492",
      "entry": "@trusted-partner.com",
      "type": "domain",
      "domain": "clientcorp.com",
      "added_at": "2026-02-01T14:22:00Z",
      "added_by": "[email protected]",
      "notes": "Accounting partner — invoices frequently quarantined"
    }
  ],
  "total": 12,
  "page": 1,
  "limit": 200
}

Add Allowlist Entry

spamtitan_manage_allowlist

Parameters:

• action — add or remove
• entry — The sender address, domain, or IP to allowlist
• domain — Client domain scope (omit for global)
• notes — Reason for adding (strongly recommended for audit trail)

Example — Add email address to allowlist:

{
  "action": "add",
  "entry": "[email protected]",
  "domain": "clientcorp.com",
  "notes": "CRM notification emails — quarantined due to bulk mail score"
}

Example response:

{
  "success": true,
  "id": "al-00499",
  "entry": "[email protected]",
  "type": "email",
  "domain": "clientcorp.com",
  "added_at": "2026-03-02T11:15:00Z"
}

Example — Remove an entry from allowlist:

{
  "action": "remove",
  "entry": "[email protected]",
  "domain": "clientcorp.com"
}

List Blocklist Entries

spamtitan_list_blocklist

Parameters:

• domain — Filter entries for a specific client domain (omit for global entries)
• type — Filter by entry type (email, domain, ip)
• page — Page number (1-based)
• limit — Results per page

Example response:

{
  "entries": [
    {
      "id": "bl-00201",
      "entry": "@persistent-spammer.net",
      "type": "domain",
      "domain": null,
      "scope": "global",
      "added_at": "2026-02-28T09:00:00Z",
      "added_by": "[email protected]",
      "notes": "Confirmed spam campaign — multiple clients targeted"
    },
    {
      "id": "bl-00202",
      "entry": "[email protected]",
      "type": "email",
      "domain": "clientcorp.com",
      "scope": "per-domain",
      "added_at": "2026-03-02T08:30:00Z",
      "added_by": "[email protected]",
      "notes": "Phishing sender — quarantined 2026-03-02 campaign"
    }
  ],
  "total": 8,
  "page": 1,
  "limit": 200
}

Add Blocklist Entry

spamtitan_manage_blocklist

Parameters:

• action — add or remove
• entry — The sender address, domain, or IP to block
• domain — Client domain scope (omit for global)
• notes — Reason for blocking (required for audit trail best practice)

Example — Block a domain globally:

{
  "action": "add",
  "entry": "@confirmed-malicious.ru",
  "notes": "Confirmed phishing domain — identified in multiple client incidents 2026-03-02"
}

Example response:

{
  "success": true,
  "id": "bl-00209",
  "entry": "@confirmed-malicious.ru",
  "type": "domain",
  "scope": "global",
  "added_at": "2026-03-02T12:00:00Z"
}

Example — Remove a blocklist entry (e.g., false positive block):

{
  "action": "remove",
  "entry": "[email protected]"
}

Common Workflows

Resolving a Quarantine False Positive with Allowlisting

1. Identify the falsely quarantined sender via the quarantine queue
2. Confirm the sender is legitimate by reviewing headers, links, and content
3. Call spamtitan_list_allowlist to check if the sender is already listed (may need to be updated)
4. Call spamtitan_manage_allowlist with action=add and the sender address or domain
5. Release the quarantined message with spamtitan_release_message
6. Document the allowlist entry with a clear notes value explaining why the sender is trusted

Blocking a Persistent Spam Campaign

1. Identify the spam sender from the quarantine queue or a user complaint
2. Check if other clients are receiving the same mail (cross-domain pattern)
3. Decide on scope: per-domain if only one client is affected, global if multiple clients are targeted
4. Call spamtitan_manage_blocklist with action=add and include descriptive notes
5. If blocking a domain rather than a single address, confirm the domain is not a legitimate shared sending service (e.g., never block @gmail.com)
6. Delete any existing quarantined messages from the same sender with spamtitan_delete_message

Reviewing and Auditing List Entries

1. Call spamtitan_list_allowlist and spamtitan_list_blocklist for each client domain
2. Review entries older than 6 months — vendors and partners may have changed, and allowlist entries should be periodically revalidated
3. Look for overly broad domain allowlists that may create a security risk (e.g., allowlisting an entire popular domain)
4. Remove stale entries with spamtitan_manage_allowlist or spamtitan_manage_blocklist using action=remove
5. Document the review in the client's PSA ticket for compliance records

Blocking After a Phishing Campaign

1. After identifying and deleting a phishing campaign in the quarantine queue, note the sending domain and IP
2. Add the sending domain to the global blocklist with spamtitan_manage_blocklist
3. If the phishing mail arrived from a specific sending IP, also blocklist the IP address
4. Check whether any related domains (typosquats or same registrant) should also be blocked
5. Verify the block is effective by checking subsequent quarantine entries — the sender should no longer appear

Error Handling

Duplicate Entry

Cause: Attempting to add an entry that already exists in the list Solution: Call spamtitan_list_allowlist or spamtitan_list_blocklist to check existing entries before adding

Entry Not Found on Remove

Cause: Attempting to remove an entry that doesn't exist or uses a different format than what was added Solution: List the current entries and use the exact entry value that appears in the list response

Invalid Entry Format

Cause: Submitting an improperly formatted email address, domain, or IP Solution: Ensure domains use the @domain.com format; IP addresses must be valid IPv4 or IPv6; email addresses must include both local part and domain

Permission Denied on Domain

Cause: API key does not have permission to manage lists for the specified domain Solution: Verify API key scope; use global scope or contact your SpamTitan admin to grant per-domain access

Best Practices

• Always provide notes when adding list entries — six months from now, no one will remember why a sender was allowlisted
• Prefer allowlisting specific email addresses over entire domains when possible; domain allowlisting is a broader trust grant
• Never allowlist based on a user's request alone — always verify the sender is legitimate before adding
• Review allowlists and blocklists quarterly; stale entries accumulate and become a security and maintenance burden
• For global blocklist entries, document the threat intelligence source (e.g., "Confirmed phishing — seen across 3 client accounts on 2026-03-02")
• Be cautious about blocking shared sending services (SendGrid, Mailchimp, etc.) — block the specific sending address or subdomain, not the entire service
• Cross-reference blocklist additions with allowlists — a sender cannot be in both lists simultaneously

Related Skills

• api-patterns - Authentication, pagination, and error handling
• quarantine - Quarantine queue management where list decisions originate